Chemical Kinetics · Question 21

An increase in the concentration of the reactants of a reaction leads to change in :

1. heat of reaction
2. threshold energy
3. collision frequency
4. activation energy

The rate constant for a first order reaction is 4.606 10-3 s-1. The time required to reduce 2.0 g of the reactant to 0.2 g is :

1. 200 s
2. 500 s
3. 1000 s
4. 100 s

If the rate constant for a first order reaction is k, the time (t) required for the completion of 99 % of the reaction is given by :

1. t = 4.606k
2. t = 2.303k
3. t = 0.693k
4. t = 6.909k

For the chemical reaction N2(g) + 3H2(g) 2NH3(g) the correct option is :

1. - d[N2]dt = 2 d[NH3]dt
2. - d[N2]dt = 12 d[NH3]dt
3. 3 d[H2]dt = 2 d[NH3]dt
4. - 13 d[H2]dt = - 12 d[NH3]dt

The correct difference between first and second order reactions is that

1. the rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
2. the half-life of a first-order reaction does not depend on [A]0; the half-life of a second order reaction does depend on [A]0
3. a first-order reaction can be catalysed; a second-order reaction cannot be catalysed
4. the rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations

When initial concentration of the reactant is doubled, the half-life period of a zero order reaction

1. is halved
2. is doubled
3. is tripled
4. remains unchanged.

Mechanism of a hypothetical reaction X2 + Y2 2XY, is given below : (i) X2 X + X (fast) (ii) X + Y2 XY + Y (slow) (iii) X + Y XY (fast) The overall order of the reaction will be

1. 2
2. 0
3. 1.5
4. 1

A first order reaction has a specific reaction rate of 10-2 sec-1. How much time will it take for 20 g of the reactant to reduce to 5 g?

1. 138.6 sec
2. 346.5 sec
3. 693.0 sec
4. 238.6 sec

The rate of first-order reaction is 0.04 mol L-1 s-1 at 10 seconds and 0.03 mol L-1 s-1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is

1. 44.1 s
2. 54.1 s
3. 24.1 s
4. 34.1 s

The addition of a catalyst during a chemical reaction alters which of the following quantities?

1. Enthalpy
2. Activation energy
3. Entropy
4. Internal energy